(154g) An Integrated Enzyme –Based Optical Glucose Sensor with Chemically Anchored in-Device Sensing Elements

An enzyme-based optical glucose microfluidic device is designed based on the quenching behavior of fluorophore, a ruthenium complex, towards oxygen molecules. Instead of traditionally used silicon- and glass-based material, a negative-tone high-aspect-ratio photoresist SU-8 was used as the main material of microfluidic channel structure. However, it is still a challenge to place the sensing elements before sealing the SU-8 cover layer because the temperature required for wafer bonding may cause enzyme denaturation. To avoid this, a novel in situ patterning method was introduced to covalently pattern enzyme containing hydrogel columns within the completed channels. The optimal glucose oxidase concentrations, ratio between enzyme and fluorophore loading, and the components of the materials used for fabricating the matrix were investigated. The characteristics of the sensor including the reversibility, reproducibility, and long-term stability were tested based on extensive experiment during a long time use. The principles underlying the sensing elements, like reaction kinetics of immobilized glucose oxidase, the diffusion of glucose into the PEG-DA matrix and the photobleaching of the fluorescent dyes were also studied. We anticipate that by using this technique, multiple sensing elements can be immobilized in these hydrogel microarrays within the microfluidic channels, offering a potential to create various novel biosensors for a wide range of applications.